The present invention relates to an extrusion head for two-component extruded threads, having a spinneret with high perforation density.
As is known, two-component threads are formed by mixing two different polymers, during the production of each thread, obtaining a thread in which the two components have a preset ratio.
This type of thread is currently possible with spinnerets having a limited number of perforations per square centimeter, i.e. in practice only some perforations per square centimeter, providing adequately constant distribution of the two components on the threads, whereas for the production of threads with spinnerets that have a high perforation density it is theoretically possible to manufacture two-component threads, but the distribution of the ratios between the two components is entirely random and thus very wide; i.e., statistical variance is very high.
This random distribution of the ratio between the two components is obviously bimodal if the two components have different viscosities, as usually occurs, to the point that separate spinning of the two components occurs for large viscosity differences.
Rheology allows to predict that the diameter of the threads is affected by the difference in viscosity and that threads richer in less viscous polymer have a diameter higher than the average.